SPIRO UNITS AS BUILDING-BLOCKS IN THERMOTROPIC LIQUID-CRYSTALS - SYNTHESIS AND PHYSICAL-PROPERTIES OF TERMINALLY SUBSTITUTED SPIRO[5.5]UNDECANES

A number of terminally substituted spiranes were prepared from 9-penty l-3-spiro[5.5]undecanone (7), which was obtained in a five-step synthe sis starting from 4-pentylcyclohexanone (1), using an intramolecular c yclisation with 4-toluenesulfonylmethyl isocyanide (TosMIC) as a key s tep. By a comparison of the physical data of the new spiro[5.5]undecan e derivatives I with those of several well-known, analogous substitute d compounds - solely differing in their central building unit - conclu sions regarding the effects of the spiro ring system on its mesogenic potential are drawn.